As shown in FIG. 1, typical network construction for assigning Internet Protocol version 6 (IPv6) address prefix by DHCPv6 PD (Dynamic Host Configuration Protocol version 6 Prefix Delegation) includes a residential gateway (RG) or a customer premise equipment (CPE). The RG or CPE serves as a requesting router, and connects a home network of a subscriber and an external network service provider (NSP) network. The RG or CPE is connected with an access node (AN), which serves as a DHCPv6 lightweight relay agent, by various access technologies, such as digital subscriber line (DSL) and passive optical network (PON) technologies. Multiple ANs are connected to a broadband remote access server (BRAS) or a broadband network gateway (BNG) device. The BRAS or BNG serves as a DHCPv6 relay agent, and is connected to the network of NSP. A DHCPv6 server, which is configured in the NSP network, are used for assigning IPv6 addresses or IPv6 address prefixes for requesting routers. A prefix pool, which is used for assigning IPv6 address prefixes for requesting routers by DHCPv6 PD, is configured on the DHCPv6 server. The prefix pool is a set of IPv6 address prefixes. For example, a prefix pool is 2001:0EFF:1B00::/40 and a prefix length of each prefix in the prefix pool is 56, then the prefix pool is a set of 65535 prefixes of prefix/56 from 2001:0EFF:1B00:0100::/56 to 2001:0EFF:1BFF:FF00::/56.
By taking BRAS as an example, in order to guarantee that a message received from the network is enable to be correctly routed to a subscriber computer in home network, for each IPV6 prefix which is assigned to a RG by a DHCP server in the DHCP PD way, an indirect routing named as a requesting router prefix routing, with the IPV6 prefix as a destination address, is needed to be established on the BRAS. For example, a prefix pool is 2001:0EFF:1B00:/40 and a prefix length of each prefix in the prefix pool is 56, then 65535 prefixes of prefix/56 from 2001:0EFF:1B00:0100::/56 to 2001:0EFF:1BFF:FF00::/56 are able to be assigned in total. In case all the prefixes of the prefix pool are assigned, 65535 requesting router prefix routings whose prefix lengths are 56 are needed to be established on the BRAS. A requesting router prefix routing table established on the BRAS is depicted in table 1, in which a destination address of a requesting router prefix routing is an assigned address prefix, a next hop address is a WAN port address of a RG and an output interface is a communication interface between the BRAS and the RG.
TABLE 1BRAS routing tableNextDestination AddressHop AddressInterface2001:0EFF:1B00:0100::/56RG1 WANCommunication interfaceport addressbetween BRAS and RG12001:0EFF:1B00:0200::/56RG2 WANCommunication interfaceport addressbetween BRAS and RG2. . .2001:0EFF:1BFF:FF00::/56RGn WANCommunication interfaceport addressbetween BRAS andRGn
In order to guarantee a correct routing of a message with the above prefix as a destination address, the BRAS needs to advertise the above routing information to the network by a routing protocol. The requesting router prefix routing information advertised by the BRAS in the network is shown as in table 2, in which a destination address of a requesting router prefix routing is an assigned address prefix and a next hop address is a BRAS network side interface address.
TABLE 2Requesting router prefix routing information advertised bythe BRAS in the networkDestination AddressNext Hop Address2001:0EFF:1B00:0100::/56A BRAS network side interface address2001:0EFF:1B00:0200::/56A BRAS network side interface address. . .2001:0EFF:1BFF:FF00::/56A BRAS network side interface address
In the prior implementing methods, a BRAS needs to advertise tens of thousands of requesting router prefix routings to a RG in the network by routing protocol, and too many routings advertised on the BRAS leads to huge number of routing table entries in a backbone network in the prior art.